Electrokinetic Remediation Technique Research Articles

Effect of Voltage variation on the Geotechnical Properties and Removal Efficiency of Heavy Metal Contaminants from Contaminated Soil using Electrokinetic Remediation Technique

A lot of research work has shown that despite the effectiveness of the electrokinetic remediation technology in decontaminating heavy metal contaminated soils, more work is still required to fully understand the role of voltage in the remediation process. There is need to establish the optimum voltage that would best remove heavy metals from such contaminated soil and its attendant effect on the geotechnical properties of the remediated soil. Effect of voltage variation on the removal efficiency of lead, copper and the geotechnical properties of remediated heavy metal contaminated soil using electrokinetic remediation technique was investigated in this research. The contaminated soil was remediated by applying direct current (DC) to the remediation setup at 0.5V/cm, 1.0V/cm, 1.5V/cm and 2.0V/cm. The concentration of the heavy metals after remediation were determined using the Oxford Instrument Analyzer to evaluate removal efficiency, geotechnical properties tests were also conducted on the soil specimens at each phase of remediation. The results showed that the lead removal efficiency was highest at 2.0V/cm (86%) with the shortest remediation time of 5days and lowest at 0.5V/cm (39%) at 9days. 52% of copper was removed at 2.0V/cm in 5days and 29% at 0.5V/cm after 9days of remediation. At 1.0V/cm, the lead and copper removal efficiency are 75% and 40% respectively. There was no significant change in the Specific Gravity of all the soil samples with the test results lying between 2.0 and 2.2. The soil is generally silty fine sand with not less than 40% passing the sieve no.200 (75micron). 45% passed through sieve 75micron for unremediated soil and slightly reduced to 40%, 40.4% and 40.2% for 30V, 45V and 60V respectively. The soil is non-plastic with the liquid limit of between 25.8% and 29.5% belonging to the A-4 group of soil. The maximum dry density improved across all the three compactive efforts, from 1.8390g/cm3 to 1.8480g/cm3 with WAS compactive effort and from 1.8000g/cm3 to 1.8320g/cm3 with BSL method with an average optimum moisture content of 10%. The CBR values increases with increase in voltage applied. The unsoaked CBR values averagely increased with 31%, 18% and 7% for BSH, WAS and BSL compactive efforts respectively. The durability index with resistances of 89% and 90% to loss in strength was recorded at 1.0V/cm and 1.5V/cm respectively, this, when compared to the resistance to loss in strength of 71% in unremediated soil has respectively 25.3% and 26.8% durability advantages. There was also a consistent increase in the UCS values, from 381kN/m2 to 474kN/m2 and from 351kN/m2 to 447kN/m2 when WAS and BSL methods of compaction were used. Generally, there was improvement in the geotechnical properties of the remediated soil. These improvements are maximum at 1.0V/cm and 1.5V/cm with little or no further improvement at 2.0V/cm. It is recommended that 1.0V and 1.5V are suitable for remediation purpose since it requires low energy consumption.

Metal Ions Removal from Aqueous Media Using an Electrokinetic Cell

Electro-kinetic (EK) remediation is a technique used for the treatment of contaminated soil and groundwater [1-2]. It involves the application of a low voltage-electrical current through the soil, which causes the movement of charged contaminants towards electrodes, where they can be extracted or immobilized. In EK remediation, electrodes are placed in the soil or contaminated water and connected to a power supply. In case of soil, soil need to be wetted with an electrolyte solution to facilitate the movement of charged particles. When a low voltage-electrical current is applied, it creates an electric field that drives the migration of charged contaminants, such as heavy metals ions and or charged organic pollutants, towards the opposite charge electrodes. The anode is typically made of a reactive metal, such as iron, while the cathode can be made of stainless steel or graphite. The electrodes are connected to a power supply that applies a low-voltage electrical current to the system. The contaminants can then be collected or treated using various methods, such as adsorption, precipitation, or electrochemical reactions [3-10]. EK remediation has several advantages over traditional remediation methods, such as in situ chemical oxidation and pump-and-treat systems. It can be applied to a wide range of contaminants and soil types, and is generally more effective at removing contaminants that are difficult to treat using other methods. Additionally, EK remediation can be a cost-effective and environmentally friendly option for the treatment of contaminated sites. This study explores the removal of cobalt (II) ions from aqueous solution combining the use of adsorbents such as zeolite placed in an electrokinetic cell. The most effective removing is almost 93% of cobalt (II) ions from aqueous solution after 300 minutes at 15 V in the presence of Faujasite type zeolites. Therefore, EK remediation technique has shown promise as an innovative approach to environmental remediation. References Omar H. Elsayed-Ali, Hani E. Elsayed-Ali and Tarek M. Abdel-Fattah, Journal of Hazardous Materials, 185 (2-3), 1550-1557 (2011)Alya Elsayed-Ali, Tarek Abdel-Fattah, Hani Elsayled-Ali, Hani, Journal of Chemical Education, 88(8), 1126-1129 (2011).TM Abdel-Fattah, ME Mahmoud, Chemical engineering journal 172 (1), 177-183 (2011)TM Abdel-Fattah, ME Mahmoud, MM Osmam, SB Ahmed, Journal of Environmental Science and health, part A 49 (9), 1064-1076 (2014)ME Mahmoud, TM Abdel-Fattah, MM Osman, SB Ahmed, Journal of Environmental Science and Health, Part A 47 (1), 130-141 (2012)TM Abdel-Fattah, B Bishop, Journal of Environmental Science and Health, Part A 39 (11-12), 2855-2866 (2004)ME Mahmoud, MM Osman, SB Ahmed, TM Abdel-Fattah, The Scientific World Journal 2012 (2012)ME Mahmoud, SS Haggag, TM Abdel-Fattah, Polyhedron 26 (14), 3956-3962 (2007)ME Mahmoud, AA Yakout, MT Abed El Aziz, MM Osman, TM Abdel-Fattah, Journal of Environmental Science and Health, Part A 50 (10), 1072-1081 (2015)H Namkoong, E Biehler, G Namkoong, TM Abdel-Fattah, ACS omega 7 (44), 39931-39937 (2022)

Incidence of Electric Field and Sulfuric Acid Concentration in Electrokinetic Remediation of Cobalt, Copper, and Nickel in Fresh Copper Mine Tailings

In the present study, the assessment of heavy metal contaminant migration from fresh mine tailings was conducted using the electrokinetic remediation technique (EKR). In this sense, a pilot EKR cell was designed to evaluate the recovery potential of copper, nickel, and cobalt species. In particular, the focus was on the impacts of electric field intensity and pH in initial mixture and testing their interaction in copper, nickel, and cobalt migration. Experiments were made using a 22 factorial experimental design with a central point, using DC electric fields from 1.0 to 2.0 V cm−1 and H2SO4 pretreatment solutions from 1.0 to 2.0 mol L−1, along with an ANOVA test with error reduction. The metal removal rates were approximately 7% for cobalt, neglectable for copper, and 6% for nickel. In the best cases, the highest concentrations by migration at the cathodic zone were 11%, 31%, and 30%, respectively. According to ANOVA tests, factor interaction was proven for each metal in the half cell near the cathode and the closest zone from the cathode specifically. Both factors affected metal concentrations, which indicates that when the goal aims for species accumulation in a narrower section, each factor has a significant effect, and their interaction makes a proven enhancement. Thus, using 2.0 V cm−1 and 2.0 mol L−1 showed a high improvement in metal concentration in the cathodic zone.

Experimental and Numerical studies on remediation of mixed metal-contaminated sediments by electrokinetics focusing on fractionation changes.

Electrokinetic remediation technique is widely applied for the removal of heavy metal from contaminated soil, but the soil buffering capacity and fractionation of heavy metals mainly affect the cost and duration of the treatment. This study aims to treat heavy metal-contaminated sediments by electrokinetic remediation (EKR) technique by using various enhancing agents such as EDTA, [Formula: see text], HCI, [Formula: see text], acetic acid and citric acid for optimizing the cost and treatment duration. The optimum molar concentration of enhancing agent for treatment was estimated by batch experiments to maximize the dissolution of target heavy metals and reduce the dissolution of earth metals (Fe, Al and Ca) to maintain soil health. The EKR experiments were performed up to 15 days with the above enhancing agents to reduce the risk associated with heavy metals and the selection of enhancing agents based on removal efficiency was found to be in an order of EDTA > citric acid > acetic acid > [Formula: see text] > HCl [Formula: see text] [Formula: see text]. Also, a numerical model has been developed by incorporating main electrokinetic transport phenomena (electromigration and electroosmosis) and geochemical processes for the prediction of treatment duration and to scale up the EKR process. The model predicts well with experimental heavy metal removal with a MAPD of [Formula: see text] 2-18 %. The parametric study on electrode distance for full-scale EKR treatment was found in this study as [Formula: see text] 0.5 m.

Vanadium removal from spent catalyst used in the manufacture of sulfuric acid by electrical potential application

Vanadium has many industrial applications and its contribution to environmental contamination is growing every day. Spent catalyst used in the sulfuric acid production is considered a hazardous residue due to the presence of vanadium pentoxide which is the most toxic form of the vanadium. Because of this, currently, these wastes are incinerated. Thus, the removal of vanadium from catalysts is justified from environmental and economic viewpoints. The aim of this work is to evaluate the effect caused by the application of the electrokinetic remediation technique in the removal of vanadium of spent catalyst used in sulfuric acid industry when submitted to different conditions of electrical potential. The experiments were performed under 6.7 and 20.0 V m−1 constant potential gradient. The results showed that the maintenance of a potential gradient of 20.0 V m−1 resulted in an increase of 16% in vanadium removal but an increase in energy consumption per kg of remediated catalyst of about 80 times compared to the application of 6.7 V m−1. It was also observed that the intensity of the applied electrical potential modify the pH of the medium.

Numerical study of the influence of electrode arrangements in electrokinetic remediation technique.

The effectiveness of electrokinetic remediation for soils depends on several factors such as the arrangement and shape of electrodes. This paper presents a numerical study on external electrostatic field generated by seven different electrode configurations in any unbounded two-dimensional domain. The boundary condition at infinity for the voltage is approximated by the iterative algorithm that expands the domain till the limit of the specified tolerance (threshold value). The numerical results indicate that there is no unique configuration with larger effective area for all spacings between the oppositely charged electrodes. In addition, the configuration with the smallest inactive electric field strength spots for all spacings between the electrodes is not unique. Moreover, the voltage profile for all electrode configurations is nonlinear, and the external electric field strength varies widely near the electrodes. Only in the intermediate region between the electrodes the external electric field strength approaches a constant value.

The Use of Electrical Resistivity Method to Mapping The Migration of Heavy Metals by Electrokinetic

The presence of heavy metals contamination in soil environment highly needs innovative remediation. Basically, this contamination was resulted from ex-mining sites, motor workshop, petrol station, landfill and industrial sites. Therefore, soil treatment is very important due to metal ions are characterized as non-biodegradable material that may be harmful to ecological system, food chain, human health and groundwater sources. There are various techniques that have been proposed to eliminate the heavy metal contamination from the soil such as bioremediation, phytoremediation, electrokinetic remediation, solidification and stabilization. The selection of treatment needs to fulfill some criteria such as cost-effective, easy to apply, green approach and high remediation efficiency. Electrokinetic remediation technique (EKR) offers those solutions in certain area where other methods are impractical. While, electrical resistivity method offers an alternative geophysical technique for soil subsurface profiling to mapping the heavy metals migration by the influece of electrical gradient. Consequently, this paper presents an overview of the use of EKR to treat contaminated soil by using ERM method to verify their effectiveness to remove heavy metals.

Migration of Sulphate Under Different Conditions: Electro-Kinetic Remediation Technique

In the present study, an experimental investigation was carried out to study the efficiency of removal of sulphate from soil using electro-kinetic remediation technique (EK). The breakthrough time of sulphate ion was calculated under the influence of electrical gradient and without electrical gradient (soil column test). The breakthrough curves and the results of both the tests were compared. To evaluate the effectiveness of EK remediation technique, the effective diffusion coefficient and the rate of migration of ions of sulphate ion without and with electrical potential were also calculated by using available simple mathematical model. The breakthrough time at C/C0 = 0.5 and C/C0 = 1 (where C/C0 = effluent concentration/influent concentration) for the electro-kinetic test was also calculated and compared with soil column test in terms of cumulative time (h) and number of pores. From the study, the breakthrough time of sulphate under electrical gradient was observed to be less compare to column test in spite of electro-osmotic flow occurring in the opposite direction. And the effective diffusion coefficient (De) of sulphate under electrical potential was found to be significantly high compare to column test but lower than the values generally reported in literature.

The Detoxification of Heavy Metals in the Phosphate Tailing-contaminated Soil through Sequential Microbial Pretreatment and Electrokinetic Remediation

ABSTRACTIn this paper, the heavy metals (HMs) in the phosphate tailing-contaminated soil were detoxified using the microbial pretreatment in combination with electrokinetic remediation (EKR).. This study provides compelling evidence that the sequential usage of the bioleaching and electrokinetics is superior to the individual method for the detoxification of Pb, Cu, Zn, Cd, and As from the contaminated soil. In the sequential system, the detoxification efficiency of Zn was the highest and that of As was the lowest. Except the element As, the detoxification efficiencies of HMs in the sequential system were generally higher than that using the single biological treatment and EKR technique. Bioleaching, generation of the passivation, and migration direction of the ions are concluded as the factors attributable to the final results; and, the initial increase in the inoculation doping of Thiobacillus ferrooxidans considered has no obvious impact on improving the final detoxification efficiency rates.

ACIDIC REMOVAL OF METALS FROM FLUIDIZED CATALYTIC CRACKING CATALYST WASTE ASSISTED BY ELECTROKINETIC TREATMENT

Abstract - One of the main uses of catalysts in the oil industry is in the fluidized catalytic cracking process, which generates large quantities of waste material after use and regeneration cycles and that can be treated by the electrokinetic remediation technique, in which the contaminant metals are transported by migration. In this study, deactivated FCC catalyst was characterized before and after the electrokinetic remediation process to evaluate the amount of metal removed, and assess structural modifications, in order to indicate a possible use as an adsorbent material. The analyses included pH measurement and the concentration profile of vanadium ions along the reactor, X-ray microtomography, X-ray fluorescence, BET analysis and DTA analysis. The re-sults indicated that 40% of the surface area of the material was recovered in relation to the disabled material, showing an increase in the available area for the adsorption. The remediation process removed nearly 31% of the vanadium and 72% of the P

Electrokinetic Remediation Technique: An Integrated Approach to Finding New Strategies for Restoration of Saline Soil and to Control Seawater Intrusion

AbstractMany applications of electrokinetic remediation have focused on the removal of heavy metals. However, the application of electrokinetic technology in salt removal from contaminated soils and groundwater has not been extensively explored. Given the current global challenge and the impact of soil and groundwater salinity, it is tempting to suggest that the research community should apply this technology to generate in‐depth knowledge for determining the feasibility and efficiency of electrokinetic remediation in salt removal, particularly in addressing seawater intrusion in coastal aquifers, which is creating growing challenges in the freshwater supply, mainly in coastal and arid regions, in view of growing populations, economic and industrial growth, and climate change. This Review shows that there is a need to begin formulating a knowledge base about categories of materials, efficiencies, and limitations. Furthermore, the viability of this technology in the real field suggests a need to gain more insight into electrokinetic applications in this area. The versatility of electrokinetic remediation in different settings is demonstrated in this Review, as is its capability to address diverse remediation challenges. The available literature is critically assessed; novel and improved electrokinetic remediation and the important trends in this field are outlined. The Review aims to summarize the evolution and current status of electrokinetic remediation research with a view of starting a debate around the possibility of applying it as a pretreatment mechanism to control seawater intrusion.

Electroremediation of heavy metals in sewage sludge

This paper presents the application of electrokinetic remediation in the treatment of sludge in a sewage treatment station. The study consisted of, in a first step, the characterization of physicochemical parameters of sludge and, in a second step, the implementation of the electrokinetic remediation technique. The concentrations of Cu, Cr, Pb and Zn in sludge samples, before and after the experiment, were determined by atomic absorption spectroscopy. After 40 hours of experiment, considering an electrolyte flow-rate of 1.34 L.h-1 at a voltage of 20 V, the removal rate of all the metals accompanied was over 50%; the highest removal efficiency was for Pb, with 72.49%. The results show the feasibility of using the electrochemical technique of electrokinetic remediation for metal removal from a sludge sewage treatment station.

Simultaneous removal of 2,4-dichlorophenol and Cd from soils by electrokinetic remediation combined with activated bamboo charcoal

An in situ electrokinetic remediation technique was designed by combining the uniform electrokinetic technology with a new-type of bamboo charcoal as adsorbent. A bench-scale experiment was conducted to investigate the application of this technique for simultaneous removal of 2,4-dichlorophenol (2,4-DCP) and Cd from a sandy loam at different periodic polarity-reversals. The contaminated soil was artificially spiked with 100 mg/kg 2,4-DCP and 500 mg/kg Cd. Two modes of polarity-reversal intervals of 12 and 24 h were included. After 10.5 d of operation, about 75.97% of Cd and 54.92% of 2,4-DCP were removed from soil at intervals of 24 h, whilst only 40.13% of Cd and 24.98% of 2,4-DCP were removed at intervals of 12 h. Soil water contents under two operation modes both significantly decreased, but evenly distributed spatially. Soil pH values under two operation modes were all maintained in the range from 7.2 to 7.4, close to the initial value. The electricity consumption per day was 12.24 and 11.61 kWh/m 3/d, respectively at polarity-reversal intervals of 12 and 24 h. In conclusion, at polarity-reversal interval of 24 h, electroremediation combined with activated bamboo charcoal was effective in simultaneous removal of 2,4-DCP and Cd from soil. Our results indicate a promising potential in in situ electroremediation of soils co-contaminated with organics and heavy metals.

Electrokinetic Removal of Manganese from River Sediment

Manganese was removed from naturally polluted river sediment by applying an electrokinetic remediation technique. The sediment was alkaline and had 20% clay, which was mainly illite. The electrokinetic remediation experiments were performed by controlling pHs in the electrode cells and reverse electroosmotic flows were observed, i.e., water moved from cathode towards anode. Manganese accumulated in areas closer to cathode, however, other metals, such as copper, zinc and lead were mostly observed in the middle section of the sediment. As a result of reverse electroosmotic flow, the removal efficiencies of metals were low and the highest removal efficiencies of manganese, copper and lead, were evaluated as 18%, 20% and 12%, respectively. Almost no removal of zinc was observed in all electrokinetic remediation experiments.

동전기법에 의한 광산퇴적토의 중금속 제거 특성

Electrokinetic remediation technique offers the opportunity to extract heavy metals from soils with high plasticity. The experiment demonstrated the applicability of electrokinetic remediation on metal-mining deposit and the decision of the enhancement method for four kinds of bench-scale studies. According to the sequential extraction of heavy metals in the "I" mining deposit, Pb and Cu were mostly associated with residual fraction and Zn and Cd were associated with water soluble and residual fraction. Therefore, removable fractions by electrokinetic technology was determined by the sum of the fraction of water soluble and exchangeable, which is Cu : 19.53%, Pb : 1.42%, Cd : 52.82%, Zn : 57.28%, respectively. When considering electrical potential, volume of effluent, soil pH, and eliminated rate of contaminant, results determined by sum of each weight were Citric aic+SDS (13) > 0.1N <TEX>$HNO_3$</TEX> (10) > HAc (8) > DDW (4). Therefore, citric acid and SDS mixed solution was determined the best enhancing agent for the remediation of metal mining deposit.g deposit.

EXPERIMENTAL STUDY ON THE HYDRO-CHEMICAL PROPERTY IN THE SOIL UNDER AN APPLIED ELECTRIC GRADIENT

Electrokinetic remediation technique is gaining increasing attention as one of the technologies for decontaminating soil and groundwater. In this method, however, sufficient efficiency has not been attained, because of the difficulty in controlling complex chemical reactions that retard the transport of ions. In order to understand the mass transport in the soil, the relationship between soil property and main hydrochemistry mechanism should be clarified. Three kinds of model soils were compared in terms of copper transport efficiency. Hydraulic conductivity of soils, clay content and main mechanism of ion transport were studied by laboratory experiment. The results are as follows; 1) The electrokinetic treatment is suitable for the soils that have high hydraulic conductivity and low clay content. 2) In this case, 13% of copper was removed from the system and 46% of copper was removed from 4/5 of the system. 3) It was confirmed that main mechanism of ion transport was the electromigration.

Electrokinetic remediation: Basics and technology status

Electrokinetic remediation, variably named as electrochemical soil processing, electromigration, electrokinetic decontamination or electroreclamation uses electric currents to extract radionuclides, heavy metals, certain organic compounds, or mixed inorganic species and some organic wastes from soils and slurries. An overview of the principals of the electrokinetic remediation technique in soils is presented. The types of waste and media in which the technology could potentially be applicable are outlined and some envisioned environmental uses of conduction phenomena in soils under electric fields are presented. The current status of the electrokinetic remediation technique and its limitations are discussed through a review of the bench-scale and pilot-scale tests. The recent findings of research on different techniques that may improve the technology's effectiveness are mentioned and the status of ongoing efforts in wide-scale implementation and commercialization of the technique in the USA are described.